Machine for pressure casting of materials



May 4, 1943.

P. R. BRADLEY MACHINE FOR PRESSURE CASTING OF MATERIALS Filed April 9, 1941 5 Sheets-Shed'I BY 9. @42223.19 y?? #WORM-'x May 4, l943- I P. R. BRADLEY 2,318,366

MACHINE FOR PRESSURE CASTING OF MATERIALS Filed April 9, 1941 5 sheets-sheet 2 May 4, ,1943. P. R. BRADLEY 2,318,366

MACHINE FOR PRESSURE CASTING OF MATERIALS Filed April 9, 1941 5 Shee'tS-Shee'l'l 5 TTOF/vey May 4, 1943- P. R. BRADLEY MACHINE FOR PRESSURE CASTING OF MATERIALS Filed April 9, 1941 5 Sheets-Sheet 4 May 4, 1943.

IP. R. BRADLEY 2,318,366 `MCHIE FOR PRESSURE CASTING 0F MATERIALS Filed April 9, 1941 5 ASheets-Sheet 5 17 A 4545 48' Hgh.

Patented May 4, 1943 MACHINE FOR PRESSURE CASTING F MATERIALS Percy Reginald Bradley, Eccleston Park, Prescot, England Application April 9, 1941, Serial No. 387,719 In Great Britain January 27, 1941 Claims.

'I'he present invention relates to die-casting machines, and has for its primary object the provision of means enabling pressures up to substantially 700 atmospheres to be used in casting articles made from aluminium, zinc or like alloys, the increase in th normal life of a machine and arrangements for facilitating maintenance and repair Where necessary.

In the present invention and from one aspect thereof, a plunger when displaced by any desired power supply to feed molten material into the die, is isolated from the molten metal by a volume of air which must be compressed by the plunger before displacement of the molten material into the die is effected. n

By virtue of this air pocket between the plunger and the molten material the necessity for an operative sliding fit between the plunger and the cylindrical space in the usual goose-neck constituting the inlet to the die is eliminated, that is to say the cylindrical space may be substantially greater in diameter than the plunger. As a direct result the risk of seizure of` the plunger within the goose-neck is eliminated.

From another aspect of the present invention, the pot for the molten material within which the goose-neck is located and the re box for heating the metal within the pot are adapted for displacement as a unit relatively to said goose-neck, whereby the latter is maintained in contact with the molten material solely at the time of casting to reduce the risk of contamination of the molten-material and damage oi the goose-neck.

Again, the melting pot and re box as a unit may be displaced by an amount suflicient to enable the goose-neck to be withdrawn from engagement with the die in a substantially horizontal direction, thus rendering it unnecessary to dismantle any other part of `the machine when it is desired to repair or renew the goose-neck.

Means may be provided for withdrawing the re box from the machine to enable repairs to be eiected to refractories and the melting pot without dismantling any other part of the machine.

The invention is more particularly described with reference to the in which- Figure 1 is a general arrangement of a diecasting machine showing the mould and the feeding mechanism, but with the mechanism for opening and closing the moulds removed.

Figure 2 is a view partly in section showing a convenient unitary structure, comprising a pot accompanying drawings,

and lre box, in its raised position enabling molten material to be fed to the goose-neck, for

subsequent supply to the mould.

Figure 3 is a sectional view through the feeding `mechanism including the goose-neck and showing the inlet valve to the goose neck in its open position and the plunger at that end of its stroke which corresponds to its inoperative position.

Figure 4 is a similar view but showing the inlet valve closed and the plunger in that position consistent with the termination of its maximum feeding displacement.

Figure 5 is a plan view of suremembers of the therefor.

Figure 6 is a section on the line 6 6 of Figure 5 through gears for displacing one of the closure means.

Figure 7 is a section on the line 'I-'I of Figure 5 through gears constituting the drive for the other closure means. g

In the form of construction illustrated in the drawings a pair of mould halves I0, Il, are respectively connected to fixed and movable mould supports I2, I3, the former of which is secured to the main casting I4 of the machine andthe latter being displaceable in that it is slidable upon spindles I5 under the control of any power means (not shown) which spindles in turn are supported between upstanding parts I6 of the main casting I4.

At the left hand of the machine a guide I'I is supported on the casting I4 and at its lower end has laterally spaced seatings for the lugs I8 of a goose-neck I9 which has an inlet valve 20, an open topped chamber 2l and an outlet duct 22 through which molten zinc, aluminium or other metal or material is into the die constituted by the mould halves I0, II. As will be seen from Figures 2, 3 and 4, the inlet duct from the valve 20 leads to the base of the open topped chamber 2l where said chamber merges into the outlet duct 22, the end of which, remote from the chamber 2|, passes through an orifice I 2a in the fixed mould support I2.

A plunger 23, which may be of carbonised mild steel having a lining or sleeve 24 of hardened alloy steel at its operative end, is adapted for reciprocation within a, sleeve 25 and the chamber 2| co-axial therewith, said displacement being under the control of any desired power means which in the vexample shown consists of a pneumatically operated piston within an air a guide for the clogoose-neck and the drive adapted to be fed is adapted to be controlled by what is hereinr after referred to as a main inlet valve plunger 3l of hardened alloy steel which, although not shown, may be internally waterA or otherwise cooled and which is prevented from rotation by a key 32. The plunger 3l is threaded at its upper end to mesh with a pinion 33 which is threaded internally and gear cut externally and forms part of a train of gears, the remainder of which are indicated at 34, 35, 36, 31 and 33, the latter gear wheel meshing with a rack 39. A retaining collar for the pinion 33 is illustrated at 40.

Similarly the sleeve 25 is prevented from rotation by a key 4I and is threaded at its upper end to mesh with a pinion 42 which forms part of a gear train, the remaining wheels of which are indicated at 43, 44, 45, 45 and 41, the latter gear wheel meshing with a rack 48.

The rack 39. the longitudinal displacement oi which causes vertical displacement of the main inlet valve plunger 3l and the rack 48 the longitudinal displacement of which raises or lowers the sleeve 25, have a lost motion connection with the moving carrier I3 of the mould. This lost motion connection is effected by passing the racks 39, 48, through separate brackets I on the front and rear respectively of the carrier I3 associated with the moving half I I of the mould, and by providing spaced lock nuts 49, 50 on the threaded end of each rack located on opposite sides of a bracket 5I. As can be seen from Figure 1 the moving carrier I3 may have an initial displacement in the opening direction vof the mould before the bracket 5I comes into contact with the stop 50 to draw the rack 48 with it and thus displace the sleeve in a direction co-axially ol the open topped chamber 2l. A similar arrangement on `the carrier I3 provides the lost motion connection with the rack of the main inlet valve plunger 3|. It will be appreciated that the gear train including the racks may be replaced by other power transmission means.

The limiting position of the plunger sleeve 25 in the downward direction of displacement is determined by the valve seating 52 located at the upper end of the chamber 2| which, as will be seen from Figure 4 ot the drawings, exceeds the diameter of the plunger 23, by an amount which is greater than is required to permit, of a sliding ilt between the plunger 23 and the inner walls of the chamber 2l and thereby prevents binding engagement between the plunger and the chamber walls. The molten zinc, aluminium or other metal `or material which is to be fed through the goose-neck to the mould I0, Il `is housed within a melting pot 53 of graphite or the like material which melting pot forms part of a unitary structure including a ilre box 54,

said lirev box and pot being mounted on a raml rear side of the- 55 of an air cylinder 58 supplied with compressed air through a valve (not shown). the arrangement being such that on elevation of the ram head within the cylinder the fire box and pot as a unit are brought to the position shown in Figure 2 of the drawings, i. e., shrouding the lower end of the goose-neck so that the level of material 51 within the melting pot lies above the inlet valve 20 of the goose-neck.

The unitary structure constituted by the melting pot and flre box is provided with external projections which in the vertical displacement ofl the structure relatively to the machine casting I4 and the goose-neck are guided by ribs 58 formed on the machine casting I4, said ribs terminating at a height above brackets 59 which is sulcient to enable each vof the projections on the ilre box structure to leave its track between the ribs of a pair and enable the whole of the unitary structure to be withdrawn horizontally through an opening 33 at one end of the casting i4 by the exertion of a pull on the handle 60 secured to the re box.-

It will be appreciated that removal of the goose-neck from engagement with the stationary mould support I2 for repair or other purposes is facilitated when the unitary structure embodying the fire box and pot is at its lower position or has been withdrawn through the opening 83.

The fire box is lined with the usual refractory material 5I and has the usual chimney 62.

In operation, with the pot 53 and hre box 54 in their raised positions, i. e., when the Vmolten material has been sufficiently elevated te enter the goose-neck throu h the inlet ductI 20 to fill the chamber 2I and he outlet duct 22 up to a level equal to that of the material within the pot, the mould halves I0, II, are-closed by movement of the carrier I3 in a direction to the left (Fig. l) and in such position the mould halves are maintained closed by any desired mechanism not shown). By virtue of this relative movement between the fixed and moving supports I2, I3, of the mould halves III, II, the racks 39, 48 are longitudinally displaced respectively to rotate the pinions 33, 42 and thus by virtue of the quick threaded engagement between thev main inlet valve plunger 3I and the pinion 33 and between the plunger sleeve 25 and the pinion 42, the plunger 3| and sleeve 25 are respectively forced downwardly to close the valve 20 and to contact with the seating 52. In this position of the sleeve 25 the upper end of the open topped chamber 2I is closed to al1 except the plunger 23, that is to say, it is air sealed with a pocket of air lying between the material in the chamber 2I and the operative lower end of the plunger which, in this position of the parts still remains above a cast iron cover 64 as shown in Figure 3.

Preferably the elevation of the unitary structurd constituted by the melting pot 53 and the fire box 54 to the position in which the molten material 51 in the pot has access to the gooseneck through the inlet chamber 20 is slightly in advance of the downward travel of the plunger 3| and sleeve 25, the lead being just sufficient to enable the material to flow into the goose-neck in time to charge this prior to closure of the valve and the chamber.

Having closed the inlet 20 to the goose-neck and provided a seal against the escape of compressed air from the top of the chamber 2|. the plunger under the control of the piston within the air cylinder 2liv is depressed to compress the air in the pocket between it and the upper surface of the molten material and to force the latter with the air pocket intervening so that at least a portion of the material is caused to enter the mould. Where the volume of material to be fed to the mould is small in comparison with the volumetric displacement of the plunger 3 it will be appreciated that the feed to the mould can be completed before the plunger actually enters the lchamber 2|, but where the mould is fed with a volume of material substantially equal to the volumetric displacement of the plunger to its maximum extent, then to complete the feeding of the material to the mould the plunger will descend to the position shown in Figure 4. Thus the stroke of the plunger depends entirely on the relative volumes of the material to be fed to the mould and its own volumetric displacement.

It will also be appreciated that in depressing the plunger to feed the material into the mould the pressure utilised in this is not limited as in the usual machines for die-casting zinc or alu-y minum, whilst again, at no time does the plunger come into contact with the molten material itself nor with the Walls of the chamber 2| and in consequence, quite apart from the elimination of the possibility of the plunger seizing, there is no possibility of corrosion of the plunger lby the molten material under treatment with the result that its life is increased and the cost of maintenance considerably reduced. 'I'he fire box and melting pot unit may be lowered immediately the valve 20 has been closed and the seal eilected at the upper end of the chamber 2| so that the goose-neck itself can be kept out of contact with the molten material at all times except during the actual charging period. Thus, while the casting is being cooled in the mould the goose-neck may -be free externally of the material, thereby reducing the effects of corrosion.

After the casting has been cooled in the mould the plunger 23 is raised to its former position, shown in Figure 3, whereupon the mould halves are opened vand simultaneously the plunger 3| and sleeve 2`5 are raised to the positions also shown in Figure 3 where the parts are ready for the next cycle of operations.

It is possible with this machine when using aluminium or zinc alloys to apply pressure of 10,000 lbs. per square inch thus obviating the existing methods of direct air pressure casting, which is limited to the air pressures obtaining in the air pipe line to the machine, or of hand ladling into a cylinder prior to a casting operation.

I declare that what I claim is:

1. A pressure casting feed device comprising a plunger, an open topped chamber of a greater diameter than is necessary for providing a, sliding fit between it and the plunger and having two base ducts respectively for the inlet of molten material and the ejection thereof, means to feed molten material to said late the said material from its supply, means to seal the open top of the chamber, except Ito the plunger itself, leaving an air pocket between the plunger and the molten material, and power operated means for displacing the plunger towards but not in contact with the air in the pocket between them and thus, on continuing the plunger displacement, to deliver molten material through the exit duct f said chamber for feeding to a mould.

2. A pressure casting feed device comprising a pot for the molten material, a rising conduit for said molten material from the pot to a mould, a vertically disposed chamber, means to isov the material to compress open-topped chamber which merges at its lower end in said conduit and which extends upwardly beyond the level of material which gravitationally ows from the pot into the stantially smaller cross section than and displaceable longitudinally of said chamber with an air cushion between the plunger and the molten material for forcing said material towards the exit end of the conduit for feeding into the mould.

3. A pressure casting feed device comprising a pot for molten material, material i-n said pot, a goose-neck supported with its lower end within said pot and including an mould.

4. A pressure casting feed device as claimed in claim 3 and wherein the means for partially filling the goose-neck with molten material comprises power operated means for raising the pot and lire box as a unit relatively to said gooseneck to a position wherein thelevel of material the inlet duct for the gooseneck chamber.

5. A pressure casting feed device as claimed in claim 3 for closing said valve, and gear means for displacing said plungerinto contact with the valve to close the latter in synchronism with the operation of mouldclosure means.

6. A pressure casting feed and housing the plunger, seating means on the outer edge of the chamber, and power means for axially displacing said sleeve into sealing contact with said seating.

7. A pressure casting feed device as claimed in claim 3 in which the means for sealing vthe top to axially displace it on to said seating.

8. A pressure casting feed device as claimed in claim 3 and including in combination a main induct thereto. a goose-neck sealing sleeve for seal- 9. A pressure casting feed device comprising a means for heating saidl plunger, a chamber substantially of greater in-l ternal diameter than said plunger and having an exit orifice leading to a mould, means for feedingv a mass of molten material to said chamber leaving an air pocket above the mass, means independent of said plunger for sealing one end of said chamber except to said plunger, and power means for displacing said plunger axially of said chamber without engaging the walls thereof to displace said mass of molten material with an air pocket intervening to feed at least a portion of said mass from said chamber into the mould.

10. A pressure casting feed device comprising a pot for molten material, a fire box for heating said material in said pot, a goose neck one end of which is operatively located within said pot for the gravitational withdrawal of a mass of molten material from the pot into the goose neck,

. means for isolating said mass from the supply within the pot, one end of said goose neck, means to seal the open end of said chamber to form a conned air space bounded on one surface by said isolated mass, plunger means of substantially lesser section than said chamber for bodily displacing said isolated mass with the air space intervening to feed at least a portion of said isolated mass from said goose neck into a mould, and means for lowering said fire box and said pot as a unit away from and towards said goose neck between successive gravitational withdrawals of molten charges from the pot to the goose neck.

PERCY' REGINAL'D BRADLEY.

an open chamber connected tov 

